I have 6 fields with the primary as ID and is set to auto_increment. I want to INSERT a new row if DATE and FROM do not match. I was thinking of REPLACE INTO or ON DUPLICATE KEY UPDATE but from what I know I have to have one of them as my Primary? I don't care how its done I just need some help with a query that would work.
ID
DATE
STORE
TOTAL
NPS
FROM
What you need is a unique index composed of both the DATE and FROM fields.
ALTER TABLE table ADD UNIQUE INDEX(DATE, FROM);
Then you can use this type of query:
INSERT IGNORE INTO table (columns) VALUES (...)
The IGNORE statement will skip any INSERT that would otherwise cause a duplicate key error.
Related
I have a table that looks like the following
Basically I want to check if the combination of (score_id, rater, rated) already exists in the database, if it does, then I update the score field, otherwise I insert a new record into the DB.
I tried INSERT ON DUPLICATE KEY UPDATE but it only works on the primary key. I'm looking for something similar but works on the values in other columns.
Solved it by creating a unique key on those three columns with alter table scores add unique key 'score_record' ('score_id', 'rater', 'rated');
Hello I am using the "INSERT ON DUPLICATE KEY UPDATE" sql statement to update my database.
All was working fine since I always inserted an unique id like this:
INSERT INTO devices(uniqueId,name)
VALUES (4,'Printer')
ON DUPLICATE KEY UPDATE name = 'Central Printer';
But for now, I need to insert elements but I don't insert a unique id, I only insert or update the values like this:
INSERT INTO table (a,b,c,d,e,f,g)
VALUES (2,3,4,5,6,7,8)
ON DUPLICATE KEY
UPDATE a=a, b=b, c=c, d=d, e=e, f=f, g=g;
Have to say that an autoincrement primary key is generated always that I insert a row.
My problem is that now the inserted rows are duplicated since I don't insert the primary key or unique id explicitly within the sql statement.
What I am supposed to do?
For example, maybe I need to insert the primary key explicitly? I would like to work with this primary autoincremented key.
For recommendation from Gordon I am adding a sample case the you can see in the next image
Rows Output
In this case I add the first three rows, and then I try to update the three first rows again with different information.... Ok I am seeing the error... There is no key to compare to...... :$
Thanks for your answers,
If you want to prevent columns from being duplicated, then create a unique index or constraint on them. For instance:
create unique index unq_table_7 on table(a, b, c, d, e, f, g);
This will guarantee that the 7 columns -- in combination -- are unique.
I've been reading up on how to use MySQL insert on duplicate key to see if it will allow me to avoid Selecting a row, checking if it exists, and then either inserting or updating. As I've read the documentation however, there is one area that confuses me. This is what the documentation says:
If you specify ON DUPLICATE KEY UPDATE, and a row is inserted that would cause a duplicate value in a UNIQUE index or PRIMARY KEY, an UPDATE of the old row is performed
The thing is, I don't want to know if this will work for my problem, because the 'condition' I have for not inserting a new one is the existence of a row that has two columns equal to a certain value, not necessarily that the primary key is the same. Right now the syntax I'm imagining is this, but I don't know if it will always insert instead of replace:
INSERT INTO attendance (event_id, user_id, status) VALUES(some_event_number, some_user_id, some_status) ON DUPLICATE KEY UPDATE status=1
The thing is, event_id and user_id aren't primary keys, but if a row in the table 'attendance' already has those columns with those values, I just want to update it. Otherwise I would like to insert it. Is this even possible with ON DUPLICATE? If not, what other method might I use?
The quote includes "a duplicate value in a UNIQUE index". So, your values do not need to be the primary key:
create unique index attendance_eventid_userid on attendance(event_id, user_id);
Presumably, you want to update the existing record because you don't want duplicates. If you want duplicates sometimes, but not for this particular insert, then you will need another method.
If I were you, I would make a primary key out of event_id and user_id. That will make this extremely easy with ON DUPLICATE.
SQLFiddle
create table attendance (
event_id int,
user_id int,
status varchar(100),
primary key(event_id, user_id)
);
Then with ease:
insert into attendance (event_id, user_id, status) values(some_event_number, some_user_id, some_status)
on duplicate key
update status = values(status);
Maybe you can try to write a trigger that checks if the pair (event_id, user_id) exists in the table before inserting, and if it exists just update it.
To the broader question of "Will INSERT ... ON DUPLICATE respect a UK even if the PK changes", the answer is yes: SQLFiddle
In this SQLFiddle I insert a new record, with a new PK id, but its values would violate the UK. It performs the ON DUPLICATE and the original PK id is preserved, but the non-UK ON DUPLICATE KEY UPDATE value changes.
I am trying to use INSERT IGNORE INTO to add a row to a table if it doesn't already exist.
Here is the statement as it stands right now:
INSERT IGNORE INTO my_table (integer, date) VALUES (11111, CURDATE())
However, since I have an auto-incrementing primary key on the table (that is not part of the insert of course), it always does the insert. Is there a way to disregard the primary key so that if the integer and date are already in the table it will not insert another row with them?
Put a UNIQUE key on the integer and the date, or the combination of the two - whichever fits your needs. That will prevent INSERT IGNORE from inserting values that violate the UNIQUE index.
For example if you want to make the combination of the two unique:
alter table my_table add unique index(integer, date)
I am trying to insert rows into a table that has no unique field or primary key. How can I write a query that will simply ignore the insert if there already exists a row with the exact same values on all fields -- a duplicate row?
Thanks.
You must have a primary key or unique key defined on some column or columns in the table for uniqueness to have any meaning. Every mechanism for detecting duplicates automatically relies on this being true.
You can't do the SELECT COUNT(*)... solution because it's subject to race conditions. That is, someone could insert a duplicate row in the moment after you select and before you insert. The only way around this is to lock the table with SELECT ... FOR UPDATE or LOCK TABLES.
Uh, why not make a primary key?
Otherwise, you have to basically do SELECT COUNT(*) FROM table WHERE field1=value AND ... AND fieldN=value for before EVERY insert.